Santa Fe land iguana (Conolophus pallidus)
|Also known as:||Barrington land iguana, Santa Fe Island iguana|
|French:||Iguane terrestre de l'île Santa Fe|
|Spanish:||Iguana Terrestre De Barrington|
|Size||Length: 1 m (2)|
Classified as Vulnerable (VU) on the IUCN Red List 2007 (1) and listed on Appendix II of CITES (3).
An impressive and robust reptile, the Santa Fe land iguana is a slightly lesser-known relative of the famous marine iguanas which inhabit the Galápagos. Reaching lengths of over one metre and with a ridge of spines running from the top of the head down the back (2), the appearance of this iguana evokes the time of the dinosaurs (4). The yellow head has numerous conspicuous, large scales, much larger than those which cover the body, and a flap of skin hangs loosely from the throat. The body is largely pale yellow with brown underparts (2). Two species of land iguana are found on the Galápagos Islands (5); this species can be distinguished from its close relative Conolophus subcristatus by being more uniformly yellow in colour and having more pronounced spines (4).
Found only on the small island of Santa Fe, also known as Barrington Island, in the Galápagos (5), which covers just 24 square kilometres (6).
Both Galápagos land iguanas are adapted to live in the dry lowlands of the islands (4). On Santa Fe, the Santa Fe land iguana can be found under the tall cacti (Opuntia species) that cover the island, and amongst the dense swathe of plants that cover the ground, particularly during the wet season, obscuring the Santa Fe land iguana from view (2).
Being a cold-blooded reptile, much of the Santa Fe land iguana's day is spent regulating its body temperature. For many hours this iguana will bask in the sun and then in the midday heat it will retreat to the shade of cactus, rocks or trees (2) (6). At dusk, the iguana crawls into an underground burrow in order to conserve heat during the cooler nights (2) (6).
While young land iguanas feed primarily on insects and other arthropods, this reptile becomes more herbivorous with age, with adult land iguanas eating mainly Opuntia cacti (5). They eat both the fruit and the spiny pads of the cacti, often without removing the spines, although they can sometimes be seen scraping the spines off with their claws (4). The succulent cacti provide the iguana with much needed moisture during the dry months in its arid habitat (6). Adult iguanas supplement this plant diet with some insects, centipedes and carrion (4).
Adult males are territorial and will earn and defend a territory, measuring up to 20 metres across, through direct combat (2). Facing another male, the iguana will arch its back and swell its body in an attempt to look larger, and then aggressively butt heads, sometimes drawing blood (2). During the mating season, successful males may mate with up to seven females, each female laying her eggs within the territory of the male (2). Females dig burrows in the soil, into which they lay a clutch of around 2 to 25 eggs (6). Three to four months later, the eggs hatch and the young take up to a week to dig themselves out of the nest (2) (6). Due to predation by hawks, owls, snakes and herons, less than 10 percent of hatchlings survive (2), but should they survive, land iguanas can live for more than 50 years (6).
A remarkable relationship exists between the Santa Fe land iguana and the birds of Santa Fe Island; whilst standing high on all four legs, ground finches and mockingbirds move over, around, and under the iguana, plucking ticks and mites from its scaly skin (2) (4).
In the past, introduced animals have impacted the habitat of Santa Fe Island, which in turn may have affected the Santa Fe land iguana. Feral goats were once found on the island (7), wiping out large areas of vegetation which the iguanas depend on for food (4), but thankfully, the Galápagos National Park Service eliminated the goats from Santa Fe in 1971 (7). It has been suggested that predation by Galápagos hawks and native rats (Oryzomis species) have impacted numbers of the Santa Fe land iguana, but the observations of other scientists suggest that this is not the case. The native rats have never been seen trying to dig down to the buried iguana eggs, and whilst Galápagos hawks do prey on young land iguanas, this natural process is not likely to pose a significant threat (7)
Currently, the primary threat to the Santa Fe land iguana is the forever present possibility of feral animals being introduced to the island. The devastating effect this could have has been shown by the presence of feral dogs on Santa Cruz Island, which virtually destroyed all populations of the other Galápagos land iguana, Conolophus subcristatus (7).
Since the Galápagos National Park Service eliminated feral goats from the Santa Fe in the 1970s, the natural vegetation has recovered well and the island has remained free from any exotic species that may threaten the land iguana (7). Being a National Park and World Heritage Site, the Galápagos Islands receive much conservation attention (8), from which the Santa Fe land iguana will naturally benefit. However, its existence on just a single, small island, means that this species will always be in a vulnerable position, and it is essential that this imposing reptile is monitored so that urgent actions can be implemented should any threats arise (7).
For further information on conservation in the Galápagos see:
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- Arthropods: a very diverse phylum (a major grouping of animals) that includes crustaceans, insects and arachnids. All arthropods have paired jointed limbs and a hard external skeleton (exoskeleton).
- Carrion: the flesh of a dead animal.
- Herbivorous: diet comprises only vegetable matter.
IUCN Red List (June, 2008)
- Kricher, J.C. (2006) Galapagos: A Natural History. Princeton University Press, Princeton.
CITES (June, 2008)
- Charles Darwin Foundation. (2006) Charles Darwin Research Station Fact Sheet: Land Iguanas. Charles Darwin Foundation, Galapagos, Ecuador.
- Fitter, J., Fitter, D. and Hosking, D. (2000) Wildlife of Galapagos. HarperCollins Publishers Ltd, London.
Galapagos Conservation Trust (July, 2008)
- Christian, K.A. (1980) Endangered iguanas. Bioscience, 30(2): 76 - .
World Database on Protected Areas (July, 2008)